Deformation twinning in nanocrystalline materials
Deformation twinning in nanocrystalline materials
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DOI：
10.1016/j.pmatsci.2011.05.001
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发表时间：
2012
影响因子：
37.4
通讯作者：
Yuntian Zhu;Xiaozhou Liao;Xiaolei Wu
中科院分区：
文献类型：
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作者：
Yuntian Zhu;Xiaozhou Liao;Xiaolei Wu
纳米晶（nc）材料可以定义为具有1-100 nm范围内的晶粒尺寸的固体。与随着晶粒尺寸减小而变得更难孪生的粗晶粒金属相反，纳米晶面心立方（fcc）金属随着晶粒尺寸减小而变得更容易孪生，达到最大孪生概率，然后当晶粒尺寸进一步减小时变得更难孪生，即对孪生表现出逆晶粒尺寸效应。分子动力学模拟和实验观察表明，纳米晶金属中的形变孪晶机制与粗晶金属中的不同。因此，在纳米晶材料中观察到几种类型的变形孪晶，但在粗晶金属中没有。也有报道称，形变孪晶可用于提高纳米晶材料的强度和延展性。本文综述了纳米晶金属中形变孪晶的各个方面，包括分子动力学模拟和实验观察到的形变孪晶、孪晶机制、影响孪晶的因素、形变孪晶形核和生长的分析模型、孪晶与位错之间的相互作用以及孪晶对力学性能和其它性能的影响。这是作者的意图，这篇评论文章不仅作为一个有价值的参考，在纳米晶金属和合金领域的研究人员，但也作为一个教科书的研究生教育。
Nanocrystalline (nc) materials can be defined as solids with grain sizes in the range of 1–100 nm. Contrary to coarse-grained metals, which become more difficult to twin with decreasing grain size, nanocrystalline face-centered-cubic (fcc) metals become easier to twin with decreasing grain size, reaching a maximum twinning probability, and then become more difficult to twin when the grain size decreases further, i.e. exhibiting an inverse grain-size effect on twinning. Molecular dynamics simulations and experimental observations have revealed that the mechanisms of deformation twinning in nanocrystalline metals are different from those in their coarse-grained counterparts. Consequently, there are several types of deformation twins that are observed in nanocrystalline materials, but not in coarse-grained metals. It has also been reported that deformation twinning can be utilized to enhance the strength and ductility of nanocrystalline materials. This paper reviews all aspects of deformation twinning in nanocrystalline metals, including deformation twins observed by molecular dynamics simulations and experiments, twinning mechanisms, factors affecting the twinning, analytical models on the nucleation and growth of deformation twins, interactions between twins and dislocations, and the effects of twins on mechanical and other properties. It is the authors’ intention for this review paper to serve not only as a valuable reference for researchers in the field of nanocrystalline metals and alloys, but also as a textbook for the education of graduate students.